Larry & Denis,
This is interesting as it highlights some of the problems experienced in the old type solar refrigerators that needed batteries.
Clearly the cooling of water packs or feeezing of water packs will impact on the energy consumption of a refrigerator system. For instance in the old style PIS fridge freezers the ice pack freezing energy consumption often dominated the need for energy. In some of the better units it was possible to freeze the ice load (typically 2.4kg/24hrs) in much less time than one day and since all were capable of storing icepacks once frozen, you had to wonder how often they were being used to pull down large icepack volumes, soaking up the stored eneregy in the battery and risking starving the refrigerator compartment of energy.
I'd say from my first hand experience this was highly likely to happen on a regular basis in the field.
The other thing we used to see was manufacturers trying to use just one refrigeration circuit to cool both fridge and freezer. A tricky balance at the best of times but given the wide variation in ambient temperatures a system that is liable to catastrophic failure.
Given the above it has become safer and more practical to manufacture fridge/freezers that have two separate and unconnected refrigeration circuits. One for refrigerator and one for freezer.
The logical next step is to separate fridge and freezer allowing for greater flexibility in choice of ratio of sizes (some locations require no freezing, some the freezer volume is greater than the vaccine storage volume) and ensuring that the energy generated is more likely to keep the vaccines safe.
Incidentally, the BLF100DC using Sure Chill technology is able to cool water packs in the same compartment as vaccines are stored without effecting the vaccine temperature if required although as Denis says we would need to re-size the solar power system to take account of this extra work load.
Ian
PQS-Sheet-True-Energy-E003-019-Solar.pdfPQS-Sheet-True-Energy-E003-019-Solar.pdfPQS-Sheet-True-Energy-E003-019-Solar.pdfPQS-Sheet-True-Energy-E003-019-Solar.pdf